JP6094574B2 - Radiation-sensitive resin composition and resist pattern forming method - Google Patents

Description

  The present invention relates to a radiation-sensitive resin composition for immersion exposure and a resist pattern forming method.

  A radiation-sensitive resin composition used for microfabrication in the manufacture of integrated circuit elements, for example, generates an acid in an exposed portion by irradiation with ArF excimer laser light, and the exposed portion and unexposed portion by a reaction using the acid as a catalyst. A resist pattern is formed by causing a difference in solubility in alkaline developer between the parts.

  In recent years, the use of the immersion exposure method is expanding as a method for forming a finer resist pattern having a line width of about 45 nm. The immersion exposure method has an advantage that the depth of focus is hardly lowered even when the numerical aperture (NA) of the lens is increased, and high resolution can be obtained. The radiation-sensitive resin composition used in this immersion exposure method prevents degradation of coating film performance and contamination of lenses, etc. by suppressing the elution of acid generators from the resist film to the liquid for immersion exposure. It is required to prevent the remaining of the watermark by improving the drainage of the resist film surface and to enable high-speed scanning exposure.

  As a means for achieving them, a technique for forming an upper film (protective film) on a resist film has been proposed (see Japanese Patent Application Laid-Open No. 2005-352384). However, this technique requires a separate film formation step, and is complicated. It is. On the other hand, a technique for increasing the hydrophobicity of the resist film surface has been studied, and a radiation-sensitive resin composition containing a highly hydrophobic fluorine atom-containing polymer is known (see International Publication No. 2007/116664). .

  On the other hand, when the hydrophobicity of the resist film surface is increased in this manner, the surface wettability of the developer and the rinsing liquid is reduced, so that development of the exposed portion of the resist film and rinsing of the development residue deposited on the surface of the unexposed portion are performed. There is a tendency that the removal by is insufficient. As a result, in the resist pattern, there is a disadvantage that a development defect such as a bridge defect in which a part of the pattern is connected or a blob defect due to adhesion of a development residue occurs. For the purpose of suppressing such development defects, a technique using a polymer derived from a trifluoromethyl alcohol group-containing alkyl ester of (meth) acrylic acid has been proposed (see JP 2010-176037 A). According to this technique, the contact angle of the resist film surface with respect to a liquid such as water can be high during immersion exposure and low after development, and as a result, high-speed scanning exposure and the occurrence of development defects can be reduced. Can be combined.

  However, the conventional radiation-sensitive resin composition described above cannot sufficiently suppress the occurrence of development defects because the degree of reduction in the receding contact angle after development is still insufficient. On the other hand, it is also required to further increase the receding contact angle at the time of immersion exposure, further increase the scanning exposure speed, and improve the productivity of the immersion exposure process.

JP 2005-352384 A International Publication No. 2007/116664 JP 2010-176037 A

  The present invention has been made on the basis of the circumstances as described above. The purpose of the present invention is to increase the receding contact angle of the resist film surface during immersion exposure, to be smaller after development, and to develop development defects. An object of the present invention is to provide a radiation-sensitive resin composition for immersion exposure that can suppress generation.

（式（１）中、Ｒ^１は、水素原子又は炭素数１〜２０の１価の有機基である。Ｒ^２は、単結合、炭素数１〜２０の２価の鎖状炭化水素基、炭素数３〜２０の２価の脂環式炭化水素基、又はこれらのうちの１種若しくは２種以上と−Ｏ−とを組み合わせた基である。Ｒ^３は、水素原子又は炭素数１〜２０の１価の有機基である。Ｒ^Ａは、水素原子又は炭素数１〜２０の１価の有機基である。）The invention made to solve the above problems is
[A] a polymer (hereinafter also referred to as “[A] polymer”) having a structural unit represented by the following formula (1) (hereinafter also referred to as “structural unit (I)”), and [B] Radiation acid generator (hereinafter also referred to as “[B] acid generator”)
Is a radiation-sensitive resin composition for immersion exposure.

(In Formula (1), R ¹ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ² is a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms, R ³ is a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a group in which one or more of these are combined with —O—, and R ³ is a hydrogen atom or 1 to 2 carbon atoms. 20 is a monovalent organic group of 20. R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.)

The radiation-sensitive resin composition for immersion exposure of the present invention contains a [A] polymer and a [B] acid generator, so that the receding contact angle of the resist film is larger during immersion exposure and after development. Can be made smaller, and development defects can be suppressed. The reason why the radiation-sensitive resin composition for immersion exposure has the above-described configuration and thus exhibits the above-mentioned effects is not necessarily clear, but can be inferred as follows, for example. In other words, the group represented by —C (R ¹ ) (OR ^A ) (CF ₃ ) of the [A] polymer (hereinafter also referred to as “group (a)”) has a fluorine atom [ A] It contributes to the high hydrophobicity of the polymer. On the other hand, part of the structure of the polymer [A] is hydrolyzed by the action of an alkali developer, and the hydrophilicity is increased. In particular, when ^RA is a hydrogen atom or a base dissociable group, the OH group in alkali development has higher acidity due to the electron withdrawing property of the trifluoromethyl group bonded to the α-carbon of this group. [A] The polymer exhibits high alkali solubility. In addition, in the structural unit (I), the group (a) is present at the specific position different from the —COOR ³ group. Due to such a specific molecular structure, it is considered that the hydrophobicity, hydrophilicity and alkali solubility are effectively exhibited, and as a result, formed from the radiation-sensitive resin composition for immersion exposure. The receding contact angle on the resist film surface can be increased more than before during immersion exposure, and can be greatly reduced after development. In addition, since the receding contact angle becomes smaller after development, the developer and the rinsing liquid can make better contact with the resist film surface, and as a result, development defects are effectively suppressed.

The radiation-sensitive resin composition for immersion exposure is
[C] Polymer having a fluorine atom content smaller than that of [A] polymer (hereinafter also referred to as “[C] polymer”)
Further containing
The [C] polymer preferably has an acid dissociable group.
The radiation-sensitive resin composition for immersion exposure usually contains a [C] polymer as a base polymer in addition to the [A] polymer and the [B] acid generator. By making the fluorine atom content of the [A] polymer higher than that of the [C] polymer, the [A] polymer can be effectively unevenly distributed on the surface of the resist film. The change in the receding contact angle can be increased. Therefore, according to the radiation-sensitive resin composition for immersion exposure, the receding contact angle of the resist film can be further increased during immersion exposure, further reduced after development, and the occurrence of development defects can be further suppressed. can do.

  [A] The polymer preferably further has a structural unit containing an acid-dissociable group (hereinafter also referred to as “structural unit (II)”). When the [A] polymer further has the structural unit (II), the undissolved residue of the [A] polymer in the developer at the exposed portion can be further suppressed. As a result, the radiation-sensitive resin composition for immersion exposure can further suppress development defects.

  The radiation-sensitive resin composition for immersion exposure preferably further contains a [D] acid diffusion controller. The radiation-sensitive resin composition for immersion exposure can further improve the lithography performance such as resolution while maintaining the above-mentioned receding contact angle and the like by further containing [D] acid diffusion controller. it can.

（式（１）中、Ｒ^１は、水素原子又は炭素数１〜２０の１価の有機基である。Ｒ^２は、単結合、炭素数１〜２０の２価の鎖状炭化水素基、炭素数３〜２０の２価の脂環式炭化水素基、又はこれらのうちの１種若しくは２種以上と−Ｏ−とを組み合わせた基である。Ｒ^３は、水素原子又は炭素数１〜２０の１価の有機基である。Ｒ^Ａは、水素原子又は炭素数１〜２０の１価の有機基である。）The radiation sensitive resin composition of the present invention is
[A] a polymer having a structural unit represented by the following formula (1):
[B] a radiation sensitive acid generator, and [C] a polymer having a smaller fluorine atom content than the [A] polymer,
This [C] polymer has an acid dissociable group.

(In Formula (1), R ¹ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ² is a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms, R ³ is a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a group in which one or more of these are combined with —O—, and R ³ is a hydrogen atom or 1 to 2 carbon atoms. 20 is a monovalent organic group of 20. R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.)

  According to the radiation-sensitive resin composition, the receding contact angle on the resist film surface can be made larger, smaller after development, and the occurrence of development defects can be suppressed.

The resist pattern forming method of the present invention comprises:
Forming a resist film with the radiation-sensitive resin composition for immersion exposure,
A step of immersion exposure of the resist film through an immersion exposure liquid; and a step of developing the resist film subjected to the immersion exposure.
According to the resist pattern forming method, since the above-described radiation-sensitive resin composition for immersion exposure is used, it is possible to form a resist pattern with few development defects while increasing the scanning exposure speed.

  Here, the “organic group” refers to a group containing at least one carbon atom.

  As described above, according to the radiation-sensitive resin composition for immersion exposure and the resist pattern forming method of the present invention, a resist pattern with few development defects can be formed while increasing the scanning exposure speed. Therefore, the present invention can be suitably used for an immersion exposure process, and the productivity can be improved and the quality of a resist pattern to be formed can be improved.

<Radiation-sensitive resin composition for immersion exposure>
The said radiation sensitive resin composition for immersion exposure contains a [A] polymer and a [B] acid generator. The radiation-sensitive resin composition for immersion exposure may contain a [C] polymer, a [D] acid diffusion controller and an [E] solvent as suitable components, and does not impair the effects of the present invention. In addition, other optional components may be contained. Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer is a polymer having the structural unit (I). [A] The polymer functions as a surface-hydrophobized polymer. The “surface hydrophobized polymer” refers to a subcomponent polymer that tends to be unevenly distributed in the surface layer of the resist film to be formed by being contained in the radiation-sensitive resin composition for immersion exposure. Such a [A] polymer can be unevenly distributed in the surface layer when a resist film is formed, and the resist film surface can be hydrophobized. As a result, it is possible to perform high-speed scanning in immersion exposure.

From the viewpoint of enhancing the function as the surface hydrophobic polymer, the fluorine atom content of the [A] polymer is preferably higher than the fluorine atom content of the base polymer. As a base polymer, [C] polymer etc. which are mentioned later are mentioned, for example. [A] The fluorine atom content of the polymer is preferably 5% by mass or more, more preferably 7% by mass or more, and still more preferably 10% by mass or more. The fluorine atom content (% by mass) of the polymer can be calculated from the structure obtained by analyzing the structure of the polymer with ¹³ C-NMR.

  [A] The polymer preferably has a structural unit (II) containing an acid dissociable group in addition to the structural unit (I), and may have a structural unit (III) containing a fluorine atom, Other structural units other than the structural units (I) to (III) may be included. [A] The polymer may have one or more of these structural units. Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is a structural unit represented by the above formula (1). [A] When the polymer has the structural unit (I) and has a group (a) represented by -C (R ¹ ) (OR ^A ) (CF ₃ ) separately from the -COOR ³ group, The radiation-sensitive resin composition for immersion exposure can make the receding contact angle of the resist film larger at the time of immersion exposure, smaller after development, and can suppress development defects.
The reason why the radiation-sensitive resin composition for immersion exposure has the structural unit (I) has the above-mentioned effects is not necessarily clear, but can be inferred as follows, for example. That is, the group (a) represented by —C (R ¹ ) (OR ^A ) (CF ₃ ) of the [A] polymer has a fluorine atom, and the [A] polymer has high hydrophobicity. Contribute. On the other hand, part of the structure of the polymer [A] is hydrolyzed by the action of an alkali developer, and the hydrophilicity is increased. In particular, when ^RA is a hydrogen atom or a base dissociable group, the OH group in alkali development has higher acidity due to the electron withdrawing property of the trifluoromethyl group bonded to the α-carbon of this group. [A] The polymer exhibits high alkali solubility. In addition, in the structural unit (I), the group (a) is present at the specific position different from the —COOR ³ group. Due to such a specific molecular structure, it is considered that the hydrophobicity, hydrophilicity and alkali solubility are effectively exhibited, and as a result, formed from the radiation-sensitive resin composition for immersion exposure. The receding contact angle on the resist film surface can be increased more than before during immersion exposure, and can be greatly reduced after development. Moreover, since the receding contact angle becomes smaller after development, the contact between the developer and the rinsing liquid and the resist film becomes more effective, so that development defects are suppressed.

In the above formula (1), ^{R 1} is a monovalent organic group hydrogen atom or a C 1-20. R ² is a single bond, a divalent chain hydrocarbon group having 1 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or one or more of them. It is a group in combination with —O—. R ³ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹ and R ³ include a monovalent chain hydrocarbon group, a monovalent alicyclic hydrocarbon group, and a monovalent aromatic hydrocarbon group. Or the group etc. which combined 1 type (s) or 2 or more types and the coupling groups containing hetero atoms, such as -O-, -CO-, -OCO-, -COO-, -S-, etc. are mentioned. Some or all of the hydrogen atoms of these groups may be substituted with a fluorine atom, a hydroxy group, a carboxy group, an amino group, a cyano group, or the like.

Examples of the monovalent chain hydrocarbon group include:
Alkyl groups such as methyl, ethyl, propyl and butyl groups;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group include:
A cycloalkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group;
And cycloalkenyl groups such as cyclopropenyl group, cyclobutenyl group, cyclopentenyl group, cyclohexenyl group and norbornenyl group.

Examples of the monovalent aromatic hydrocarbon group include:
Aryl groups such as phenyl, tolyl, xylyl, naphthyl and anthryl;
Examples thereof include aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group and anthrylmethyl group.

R ¹ is a hydrogen atom, a monovalent chain hydrocarbon group, a monovalent alicyclic hydrocarbon group, a monovalent group from the viewpoint of improving the receding contact angle at the time of immersion exposure of the resist film surface to be formed. Are preferably a monovalent fluorinated alicyclic hydrocarbon group, more preferably a hydrogen atom or a monovalent perfluoroalkyl group, still more preferably a hydrogen atom or a trifluoromethyl group, and trifluoro. A methyl group is particularly preferred.

R ³ is a hydrogen atom, a monovalent chain hydrocarbon group, a monovalent alicyclic hydrocarbon group, a monovalent group, from the viewpoint of improving the receding contact angle during immersion exposure of the resist film surface to be formed. Fluorinated chain hydrocarbon group, monovalent fluorinated alicyclic hydrocarbon group is preferred, methyl group, ethyl group, cyclohexyl group, hexafluoro-2-propyl group is more preferred, hexafluoro-2-propyl group Is more preferable.

Examples of the divalent chain hydrocarbon group having 1 to 20 carbon atoms represented by R ² include a methanediyl group, an ethanediyl group, a propanediyl group, a butanediyl group, a pentanediyl group, a hexanediyl group, an octanediyl group, and a decandiyl group. , Dodecanediyl group, tetradecanediyl group, hexadecanediyl group, octadecanediyl group, icosanediyl group and the like.

Examples of the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ² include a cyclopropanediyl group, a cyclobutanediyl group, a cyclopentanediyl group, a cyclohexanediyl group, a cyclooctanediyl group, and a cyclodecanediyl group. Groups and the like.

Examples of the group in which one or more of the chain hydrocarbon group and the alicyclic hydrocarbon group represented by R ² are combined with —O— include, for example, a methanediyloxy group and ethanediyloxy. Group, propanediyloxy group, butanediyloxy group, pentanediyloxy group, hexanediyloxy group, alkanediyloxy group such as octanediyloxy group; methanediyloxymethanediyl group, methanediyloxyethanediyl group, methanediyloxy (1,2-propanediyl) group, methanediyloxybutanediyl group, methanediyloxycyclohexanediyl group and the like containing one -O-; two or more propanediyloxyethanediyloxyethanediyl groups and the like And a group containing —O—.

Among these, R ² includes a divalent chain hydrocarbon group and two divalent chain hydrocarbons from the viewpoint of improving the receding contact angle at the time of immersion exposure of the resist film surface to be formed. A group in which a group and one —O— are combined, and a divalent chain hydrocarbon group having 1 to 4 carbon atoms or two divalent chain hydrocarbon groups having 1 to 4 carbon atoms; A group in which one —O— is combined is more preferable, and a divalent chain hydrocarbon group having 2 or 3 carbon atoms or a divalent chain hydrocarbon group having 2 to 3 carbon atoms and A group in which one —O— is combined is more preferable, and an ethanediyl group, a methanediyloxyethanediyl group, and a methanediyloxy (1,2-propanediyl) group are particularly preferable, a methanediyloxyethanediyl group, and methanediyl. Even more preferred are oxy (1,2-propanediyl) groups.

When R ^A is a hydrogen atom, examples of —C (R ¹ ) (OH) (CF ₃ ) in the above formula (1) include 2-hydroxy-1,1,1,3,3,3-hexa Fluoro-2-propyl group, 1-hydroxy-2,2,2-trifluoroethyl group, 2-hydroxy-1,1,1,4,4,4-hexafluoro-2-butyl group, 2-hydroxy- Examples include 1,1,1,3,3,4,4,4-octafluoro-2-butyl group. Among these, 2-hydroxy-1,1,1,3,3,3-hexafluoro-2-propyl group and 1-hydroxy-2,2,2-trifluoroethyl group are preferable, and 2-hydroxy- A 1,1,1,3,3,3-hexafluoro-2-propyl group is more preferred.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ^A include the same groups as the monovalent organic groups exemplified as R ¹ and R ³ above. Among these, the monovalent organic group represented by R ^A is preferably a monovalent hydrocarbon group or an acyl group, more preferably an alkyl group or an acyl group, and even more preferably an acyl group. The monovalent organic group is also preferably a monovalent base dissociable group. The “base dissociable group” is, for example, a group that replaces a hydrogen atom of a hydroxy group, and in the presence of an alkali (for example, in a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution at 23 ° C.). A group that dissociates.

  Examples of the monovalent base dissociable group include a group represented by the following formula (Ba-1) and a group represented by the following formula (Ba-2).

In formulas (Ba-1) and (Ba-2), R ^Ba is independently a monovalent hydrocarbon group having 1 to 20 carbon atoms. Some or all of the hydrogen atoms of the hydrocarbon group may be substituted.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^Ba include, for example, a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and a monovalent alicyclic ring having 3 to 20 carbon atoms. And a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms, the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include And the same groups as those exemplified as R ¹ and R ³ above.

Examples of the substituent for the monovalent hydrocarbon group represented by R ^Ba include a fluorine atom, a hydroxy group, an amino group, a mercapto group, a carboxy group, a cyano group, an alkoxy group, an acyl group, and an acyloxy group. It is done.

R ^Ba is preferably a monovalent chain hydrocarbon group, more preferably a monovalent chain hydrocarbon group having 1 to 5 carbon atoms, and still more preferably a methyl group.

  Examples of the group represented by the formula (Ba-1) and the group represented by the formula (Ba-2) include a group represented by the following formula.

R ^A is preferably a hydrogen atom or a monovalent base dissociable group, and more preferably a hydrogen atom. By using ^RA as the above group, it becomes an OH group after alkali development, and has a higher acidity due to the electron withdrawing property of the trifluoromethyl group bonded to the α-carbon of this group. The coalescence shows high alkali solubility. Thereby, the receding contact angle of the resist film surface after development can be further reduced. As a result, the occurrence of development defects in the resist pattern formed from the radiation-sensitive resin composition for immersion exposure can be further suppressed.

  Examples of the structural unit (I) include structural units represented by the following formulas (1-1) to (1-18).

  Among these, structural units represented by the above formulas (1-1) to (1-9), (1-13) and (1-16) are preferable, and the above formulas (1-1) and (1-2) are preferred. ), (1-4), (1-5), (1-6) and (1-16) are more preferred, and the above formulas (1-4), (1-5) and ( The structural unit represented by 1-6) is more preferable.

As the structural unit (I), for example, a hydrogen atom of a — (CF ₃ ) ₂ C—OH group in the structural unit represented by the above formulas (1-1) to (1-18) is the above (Ba -1) or a structural unit substituted with a monovalent base dissociable group represented by the formula (Ba-2).

  The content ratio of the structural unit (I) is preferably 1 mol% or more and 100 mol% or less, more preferably 10 mol% or more and 98 mol% or less, based on all the structural units constituting the [A] polymer. It is more preferably from mol% to 95 mol%, particularly preferably from 60 mol% to 90 mol%. [A] By setting the content ratio of the structural unit (I) in the polymer within the above range, the receding contact angle of the formed resist film can be further increased during immersion exposure and further reduced after development, In addition, development defects can be further suppressed.

[A] As described later, the polymer [A] can be obtained by radical polymerization together with a monomer that gives the structural unit (I) and a monomer that gives another structural unit as necessary. The method for synthesizing the compound that gives the structural unit (I) is, for example, as follows when R ² is the following compound (i) in which —R ^2a —O— (CH ₂ ) _n —. As the compound that gives the structural unit (I) in which R ² is other than —R ^2a —O— (CH ₂ ) _n —, a known compound can be used. Examples of the known compound include compounds described in JP 2002-220420 A, JP 2002-155112 A, JP 2005-107476 A, and the like.

In the formula (i-a), (i -b) and (i), ^{R 1} is a monovalent organic group hydrogen atom or a C 1-20. R ^2a is a divalent chain hydrocarbon group having 1 to 16 carbon atoms, or a combination of this chain hydrocarbon group and —O—. R ³ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. X is a halogen atom. n is an integer of 1 to 4.

The hydroxy compound represented by the above formula (ia) and the haloalkyl acrylate compound represented by the above formula (ib) are reacted in a solvent such as dichloromethane in the presence of a base compound such as triethylamine. To obtain the compound (i) represented by the above formula. When R ^A is a hydrogen atom, in the compound represented by formula (ia), the reactivity of the hydroxy group bonded to the carbon atom adjacent to the CF ₃ group out of the two hydroxy groups is low. Compound (i) can be obtained efficiently. The compound (i) in which R ^A is a monovalent organic group can also be synthesized by converting the OH group of the compound (i) in which R ^A is a hydrogen atom into OR ^A.

  Examples of the halogen atom represented by X include a fluorine atom, a halogen atom, a bromine atom, and an iodine atom. Among these, a bromine atom is preferable from the viewpoint of reaction yield.

[Structural unit (II)]
The structural unit (II) is a structural unit containing an acid dissociable group. The “acid-dissociable group” refers to a group that replaces a hydrogen atom such as a carboxy group or a hydroxy group and dissociates by the action of an acid. [A] Since the polymer has the structural unit (II), it is possible to further suppress the undissolved residue in the developer in the exposed portion. As a result, according to the radiation-sensitive resin composition for immersion exposure, development defects can be further suppressed.

  Examples of the structural unit (II) include a structural unit represented by the following formula (2).

In the formula (2), R ⁴ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁵ is an alkyl group having 1 to 6 carbon atoms or an alicyclic hydrocarbon group having 4 to 20 carbon atoms. R ⁶ and R ⁷ are each independently an alkyl group having 1 to 6 carbon atoms or an alicyclic hydrocarbon group having 4 to 20 carbon atoms, or R ⁶ and R ⁷ are bonded to each other, Forms a divalent cyclic group together with the carbon atom to which is bonded.

R ⁴ is preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of the copolymerizability of the monomer that gives the structural unit (II).

Examples of the alkyl group having 1 to 6 carbon atoms represented by R ^{5 to} R ⁷ include, for example, methyl group, ethyl group, n-propyl, i-propyl group, n-butyl group, i-butyl group, sec- A butyl group, a t-butyl group, etc. are mentioned. Among these, a methyl group, an ethyl group, and an i-propyl group are preferable.

Examples of the alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ^{5 to} R ⁷ include monocyclic cycloalkyl groups such as a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group; Examples thereof include polycyclic cycloalkyl groups such as a norbornyl group and an adamantyl group. Among these, a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group are preferable.

Examples of the divalent cyclic group formed by combining R ⁶ and R ⁷ with each other include a monocyclic cycloalkanediyl group such as a cyclopentanediyl group, a cyclohexanediyl group, and a cyclooctanediyl group; a norbornanediyl group, an adamantane Polycyclic cycloalkanediyl groups such as diyl groups; monocyclic divalent aliphatic heterocyclic groups such as azacyclopentanediyl groups and oxacyclopentanediyl groups; polycycles such as azanorbornanediyl groups and oxanorbornanediyl groups And a divalent aliphatic heterocyclic group. Among these, a monocyclic cycloalkanediyl group and a polycyclic cycloalkanediyl group are preferable, and a cyclopentanediyl group, a cyclohexanediyl group, a cyclooctanediyl group, a norbornanediyl group, and an adamantanediyl group are more preferable, and a cyclopentane More preferred are a diyl group and an adamantanediyl group.

As the structural unit (II), a structural unit having an alkanediyl group formed by combining R ⁶ and R ⁷ with each other is preferable, and a structural unit derived from 1-alkyl-1-cycloalkyl (meth) acrylate, 2- More preferred are structural units derived from alkyl-2-adamantyl (meth) acrylate, more preferred are structural units derived from 1-alkyl-1-cycloalkyl (meth) acrylate, and 1-alkyl-1-cyclopentyl (meth) acrylate. The structural unit derived from 1 is particularly preferable, and the structural unit derived from 1-methyl-1-cyclopentyl (meth) acrylate is more particularly preferable.

  Examples of the monomer that gives the structural unit (II) include monomers represented by the following formulas (2-1) to (2-11) (hereinafter referred to as “monomer (2-1) to (2)”. -11) ")) and the like.

  Among the above monomers, monomers (2-2), (2-3), (2-4), (2-9) and (2-10) are preferred, and monomer (2-2) Is more preferable.

  As a content rate of structural unit (II), 5 mol% or more and 90 mol% or less are preferable with respect to all the structural units which comprise a [A] polymer, 8 mol% or more and 60 mol% or less are more preferable, and 10 mol % To 40 mol% is more preferable. By making the content rate of structural unit (II) into the said range, the said radiation sensitive resin composition for immersion exposure can further suppress the undissolved residue to the developing solution of the [A] polymer in an exposure part. As a result, the occurrence of development defects can be further suppressed.

[Structural unit (III)]
The structural unit (III) is a structural unit containing a fluorine atom (except for those corresponding to the structural unit (I)). [A] In the polymer, since the structural unit (I) contains a fluorine atom, the structural unit (III) is not necessarily required, but the [A] polymer further has the structural unit (III). Thus, the fluorine atom content can be increased, and as a result, uneven distribution in the resist surface layer can be promoted.

  Examples of the structural unit (III) include a structural unit represented by the formula (3-1) (hereinafter also referred to as “structural unit (III-1)”) and a formula (3-2). A structural unit (hereinafter, also referred to as “structural unit (III-2)”), a structural unit represented by formula (3-3) (hereinafter, also referred to as “structural unit (III-3)”), and the like.

In the formula (3-1), ^{R 8} represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁹ is a C 1-6 linear or branched alkyl group having a fluorine atom or a C 4-20 monovalent alicyclic hydrocarbon group having a fluorine atom. However, one part or all part of the hydrogen atom which the said alkyl group and alicyclic hydrocarbon group have may be substituted.
In the formula ^{(3-2), R 10} is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ¹¹ is a (k + 1) -valent linking group. k is an integer of 1 to 3. X is a divalent linking group having a fluorine atom. R ¹² is a hydrogen atom or a monovalent organic group. However, when k is 2 or 3, the plurality of X and R ¹² may be the same or different.
In the formula ^{(3-3), R 13} is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ¹⁴ is a linking group having no (m + 1) -valent fluorine atom. m is an integer of 1-3. A ¹ is —COO—. R ¹⁵ is a monovalent hydrocarbon group containing at least one fluorine atom. However, when m is 2 or 3, the plurality of A ¹ and R ¹⁵ may be the same or different from each other.

As a C1-C6 linear or branched alkyl group which has a fluorine atom represented by said R < ⁹ >, C1-C6, such as a methyl group, an ethyl group, a propyl group, a butyl group, is mentioned, for example. Examples include a group in which part or all of the hydrogen atoms of the linear or branched alkyl group are substituted with fluorine atoms.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms having a fluorine atom represented by R ⁹ include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, a norbornyl group, an adamantyl group, Examples include groups in which part or all of the hydrogen atoms of a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms such as a cyclopentylmethyl group and a cyclohexylmethyl group are substituted with fluorine atoms.

Examples of the (k + 1) -valent linking group represented by R ¹¹ include a linear or branched hydrocarbon group having 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to 30 carbon atoms, and the number of carbon atoms. 6-30 aromatic hydrocarbon groups, or a group in which these groups are combined with one or more groups selected from the group consisting of —O—, —S—, —NH—, —CO— and —CS—. Etc. The (k + 1) -valent linking group may have a substituent.

  Examples of the linear or branched hydrocarbon group having 1 to 30 carbon atoms include hydrocarbon groups such as methane, ethane, propane, butane, pentane, hexane, heptane, decane, icosane and triacontane (k + 1). And a group excluding individual hydrogen atoms.

Examples of the alicyclic hydrocarbon group having 3 to 30 carbon atoms include monocyclic saturated hydrocarbons such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, methylcyclohexane, and ethylcyclohexane;
Monocyclic unsaturated hydrocarbons such as cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, cyclopentadiene, cyclohexadiene, cyclooctadiene, cyclodecadiene;
Bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane, tricyclo [5.2.1.0 ^2,6 ] decane, tricyclo [3.3.1.1 ^3,7 ] decane, Tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] polycyclic saturated hydrocarbons such as dodecane and adamantane;
Bicyclo [2.2.1] heptene, bicyclo [2.2.2] octene, tricyclo [5.2.1.0 ^2,6 ] decene, tricyclo [3.3.1.1 ^3,7 ] decene, Tetracyclo [6.2.1.1 ^3,6 . And a group obtained by removing (k + 1) hydrogen atoms from a polycyclic hydrocarbon such as 0 ^2,7 ] dodecene.

  Examples of the aromatic hydrocarbon group having 6 to 30 carbon atoms include aromatic hydrocarbons such as benzene, naphthalene, phenanthrene, anthracene, tetracene, pentacene, pyrene, picene, toluene, xylene, ethylbenzene, mesitylene, cumene (k + 1). ) Groups from which a single hydrogen atom is removed.

  Examples of the divalent linking group having a fluorine atom represented by X include, for example, a divalent linear hydrocarbon group having 1 to 20 carbon atoms having a fluorine atom, and a divalent combination of this group and a carbonyl group. Groups and the like. Examples of X include groups represented by the following formulas (X-1) to (X-7).

  Among these, X is preferably a group represented by the above formula (X-7).

Examples of the monovalent organic group represented by R ¹² include a linear or branched hydrocarbon group having 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to 30 carbon atoms, and 6 to 6 carbon atoms. 30 aromatic hydrocarbon groups, or a combination of these groups and one or more groups selected from the group consisting of oxygen, sulfur, ether, ester, carbonyl, imino and amide groups, etc. Is mentioned.

Examples of the linking group having no (m + 1) -valent fluorine atom represented by R ¹⁴ include a linear or branched hydrocarbon group having 1 to 30 carbon atoms and an alicyclic group having 3 to 30 carbon atoms. A hydrocarbon group, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or a hydrocarbon group having 1 to 30 carbon atoms and -CO-, -COO-, -OCO-, -O-, -NR-, -CS- , —S—, —SO—, and —SO ₂ —, and a combination of one or more groups selected from the group consisting of —SO ₂ — and the like. Examples of the linking group having no (m + 1) -valent fluorine atom represented by R ¹³ include a fluorine atom among the groups exemplified as the (k + 1) -valent linking group represented by R ^11. Examples thereof include the same groups as those not to be used.

Examples of the monovalent hydrocarbon group containing at least one fluorine atom represented by R ¹⁵ include a fluorinated alkyl group, a fluorinated alicyclic hydrocarbon group, and a fluorinated aromatic hydrocarbon group. .

  Examples of the monomer that gives the structural unit (III-1) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, perfluoroethyl (meth) acrylate, and perfluoro n. -Propyl (meth) acrylate, perfluoro i-propyl (meth) acrylate, perfluoro n-butyl (meth) acrylate, perfluoro i-butyl (meth) acrylate, perfluoro t-butyl (meth) acrylate, perfluorocyclohexyl (Meth) acrylate, 2- (1,1,1,3,3,3-hexafluoro) propyl (meth) acrylate, 1- (2,2,3,3,4,4,5,5-octafluoro ) Pentyl (meth) acrylate, 1- (2,2,3,3,4,4,5,5-octaful B) Hexyl (meth) acrylate, perfluorocyclohexylmethyl (meth) acrylate, 1- (2,2,3,3,3-pentafluoro) propyl (meth) acrylate, 1- (2,2,3,3, 4,4,4-heptafluoro) penta (meth) acrylate, 1- (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, 10-heptadecafluoro) decyl (meth) acrylate, 1- (5-trifluoromethyl-3,3,4,4,5,6,6,6-octafluoro) hexyl (meth) acrylate and the like.

  Examples of the monomer that gives the structural unit (III-2) include (meth) acrylic acid 2- (1-ethoxycarbonyl-1,1-difluoro) butyl ester and (meth) acrylic acid 2- (1-t). -Butoxycarbonyl-1,1-difluoro) butyl ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-3-propyl) ester, (meth) acrylic acid ( 1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-butyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-) 4-cyclohexyl-4-butyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-5-pen) ) Ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester, (meth) acrylic acid 2-{[5- (1 ′, 1 ', 1'-trifluoro-2'-trifluoromethyl-2'-hydroxy) propyl] bicyclo [2.2.1] heptyl} ester and the like. Of these, (meth) acrylic acid 2- (1-t-butoxycarbonyl-1,1-difluoro) butyl ester and (meth) acrylic acid 2- (1-ethoxycarbonyl-1,1-difluoro) butyl ester are preferable.

  Examples of the monomer that gives the structural unit (III-3) include (meth) acrylic acid 2- (1,1,1,3,3,3-hexafluoro-2-propoxycarbonyl) norbornane lactonyl ester, (Meth) acrylic acid 2- (2,2,2-trifluoroethoxycarbonyl) norbornane lactonyl ester, (meth) acrylic acid 4- (1,1,1,3,3,3-hexafluoro-2-propoxy Examples include carbonyl) cyclohexyl ester, (meth) acrylic acid 4- (2,2,2-trifluoroethoxycarbonyl) cyclohexyl ester, and the like.

  Examples of the structural unit (III) include the following formulas (3-1-1) to (3-1-6), formulas (3-2-1) to (3-2-3), and formulas (3-3). Examples thereof include the structural unit represented by 1).

In the above formulas (3-1-1) to (3-1-6), R ⁸ has the same meaning as the above formula (3-1). In the formulas (3-2-1) to (3-2-3), R ¹⁰ has the same meaning as the formula (3-2). In the above formula (3-3-1), R ¹³ has the same meaning as in the above formula (3-3).

  Among these, the structural unit represented by the formula (3-1-1) and the structural unit represented by the formula (3-1-3) are preferable.

  As a content rate of structural unit (III), 0 to 90 mol% is preferable with respect to all the structural units which comprise a [A] polymer, and 0 to 50 mol% is more preferable.

  [A] The polymer may have one or more other structural units other than the structural units (I) to (III). As a content rate of another structural unit, 30 mol% or less is preferable and 20 mol% or less is more preferable.

  [A] The content of the polymer is preferably 0.1% by mass or more and 50% by mass or less, and preferably 0.1% by mass or more and 20% by mass or less with respect to the total solid content of the radiation-sensitive resin composition for immersion exposure. % By mass or less is more preferable, 0.5% by mass or more and 15% by mass or less is more preferable, and 1% by mass or more and 10% by mass or less is particularly preferable.

  [A] The content of the polymer is preferably 0.1 parts by mass or more and 20 parts by mass or less, and more preferably 0.5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the polymer [C] described later. 1 part by mass or more and 10 parts by mass or less are more preferable.

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized, for example, by polymerizing a monomer that gives each predetermined structural unit in a suitable solvent using a radical polymerization initiator.

  As a polymerization reaction method, for example, a solution containing a monomer and a radical initiator is dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction; a solution containing the monomer and a radical A method in which a solution containing an initiator is dropped into a reaction solvent or a solution containing a monomer separately to cause a polymerization reaction; a plurality of types of solutions containing each monomer, and a radical initiator For example, a method may be used in which the solution is dropped into a reaction solvent or a monomer-containing solution to cause a polymerization reaction.

  Examples of the radical initiator include 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis ( 2-cyclopropylpropionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobisisobutyrate and the like. These radical initiators can be used in combination of two or more.

Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane;
Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane;
Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene;
Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene;
Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate and methyl propionate;
Ketones such as acetone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. In addition, these solvents may use 2 or more types together.

  [A] In the polymerization reaction for synthesizing the polymer, a molecular weight modifier can be used to adjust the molecular weight. Examples of the molecular weight modifier include halogenated hydrocarbons such as chloroform and carbon tetrabromide; mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, and thioglycolic acid; Xanthogens such as xanthogen sulfide and diisopropylxanthogen disulfide; terpinolene, α-methylstyrene dimer and the like.

  As reaction temperature in the said superposition | polymerization, it is 40 to 150 degreeC normally, Preferably it is 50 to 120 degreeC. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

  The polymer obtained by the polymerization reaction can be recovered by a reprecipitation method. As the reprecipitation solvent, an alcohol solvent or the like can be used.

  [A] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 1,000 or more and 50,000 or less, more preferably 2,000 or more and 30,000 or less. Is more preferably from 3,000 to 15,000, particularly preferably from 3,000 to 10,000. [A] By making Mw of a polymer into the said range, the uneven distribution of [A] polymer to the resist film surface layer can be accelerated | stimulated, As a result, the said radiation sensitive resin composition for immersion exposure is as follows. The receding contact angle of the formed resist film can be made larger during immersion exposure and smaller after development.

  [A] The ratio (Mw / Mn) between the polymer Mw and the polystyrene-equivalent number average molecular weight (Mn) by the GPC method is preferably from 1 to 5, more preferably from 1 to 3, more preferably from 1 to 2. More preferably, 1.2 or more and 1.6 or less are especially preferable.

In addition, Mw and Mn of the polymer in this specification are measured by GPC under the following conditions.
Column: 2 G2000HXL, 1 G3000HXL, and 1 G4000HXL (manufactured by Tosoh)
Mobile phase: Tetrahydrofuran Column temperature: 40 ° C
Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

<[B] Acid generator>
[B] The acid generator generates an acid upon exposure, and the acid dissociates an acid-dissociable group contained in the [A] polymer and the later-described [C] polymer to generate a carboxyl group. As a result, the polarities of these polymers increase, and the polymer in the exposed area becomes soluble in the alkaline developer. The inclusion form of the [B] acid generator in the radiation-sensitive resin composition for immersion exposure may be a compound form as will be described later (hereinafter referred to as “[B] acid generator” where appropriate). It may be a form incorporated as part or both of these forms.

  [B] Examples of the acid generator include onium salt compounds, N-sulfonyloxyimide compounds, halogen-containing compounds, diazoketone compounds, and the like.

  Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like.

  Examples of the sulfonium salt include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept- 2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 2- (1-adamantyl) -1,1-difluoroethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenyl Sulfonium nonafluoro-n-butanesulfonate, 4-cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4- Methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl -1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantylcarbonyloxy) -hexane-1-s Honeto, and the like.

  Examples of the tetrahydrothiophenium salt include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nona. Fluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophene Nitro 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium trifluoromethane Sulfonate, 1- (6-n-butoxynaphthalene-2 Yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (6-n-butoxynaphthalene- 2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) ) Tetrahydrothiophenium trifluoromethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydro Thiophenium perfluoro-n-octance Phonates, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, etc. Can be mentioned.

  Examples of the iodonium salt include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl- 1,1,2,2-tetrafluoroethanesulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t -Butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetra Le Oro ethanesulfonate.

  Examples of the N-sulfonyloxyimide compound include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy). ) Bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2 , 3-dicarboximide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept- 5-ene-2,3-dicarboximide and the like can be mentioned.

  Among these, onium salt compounds are preferable, sulfonium salts are more preferable, triphenylsulfonium perfluoroalkane sulfonate is more preferable, and triphenylsulfonium nona-n-butanesulfonate is particularly preferable.

  [B] As the content of the acid generator, as the content when [B] the acid generator is an acid generator, the sensitivity and developability of the radiation-sensitive resin composition for immersion exposure are ensured. In view of 100 parts by mass of the polymer [A], 0.5 parts by mass or more and 20,000 parts by mass or less are preferable, 5 parts by mass or more and 10,000 parts by mass or less are more preferable, and 10 parts by mass or more and 1, 000 parts by mass or less is more preferable, and 50 parts by mass or more and 500 parts by mass or less is particularly preferable.

  Moreover, as content of [B] acid generator, from a viewpoint of ensuring the sensitivity and developability of the said radiation sensitive resin composition for immersion exposure, with respect to 100 mass parts of [C] polymer mentioned later, 0.1 parts by mass or more and 20 parts by mass or less are preferable, 0.5 parts by mass or more and 17 parts by mass or less are more preferable, and 1 part by mass or more and 15 parts by mass or less are more preferable.

  [B] By making content of an acid generator into the said range, the sensitivity and developability of the said radiation sensitive resin composition for immersion exposure can be improved. [B] The acid generator can be used alone or in combination of two or more.

<[C] polymer>
The [C] polymer is a polymer having a fluorine atom content smaller than that of the [A] polymer, and is a polymer having an acid dissociable group. [C] The polymer is a polymer that becomes a base polymer in the radiation-sensitive resin composition for immersion exposure. The “base polymer” refers to a polymer that is a main component of a polymer that constitutes a resist film formed from a radiation-sensitive resin composition, and is preferably based on the total polymer that constitutes the resist film. Refers to a polymer occupying 50% by mass or more.

  Since the fluorine atom content of the [C] polymer is smaller than the fluorine atom content of the [A] polymer, it can be effectively unevenly distributed in the resist film surface layer on which the [A] polymer is formed. As a result, the radiation-sensitive resin composition for immersion exposure can make the receding contact angle of the resist film formed larger during immersion exposure and smaller after development.

  [C] The fluorine atom content of the polymer is preferably less than 5% by mass, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

  [C] The polymer has a structural unit containing an acid-dissociable group (hereinafter also referred to as “structural unit (C-II)”). In addition to this structural unit, for example, a lactone structure, a cyclic carbonate structure, and a sultone It preferably has a structural unit having at least one structure selected from the group consisting of structures (hereinafter also referred to as “structural unit (IV)”), and has other structural units other than these structural units. It may be. [C] The polymer may have one or more of each structural unit. Hereinafter, each structural unit will be described.

[Structural unit (C-II)]
Since the [C] polymer has the structural unit (C-II), the acid-dissociable group is dissociated by the action of the acid generated from the [B] acid generator to generate a carboxyl group or the like. As a result, the polarity of the [C] polymer changes, and the solubility in the alkali developer changes.

  The structural unit (C-II) is not particularly limited as long as it has an acid dissociable group, and examples thereof include the structural unit (II) in the above-described [A] polymer.

  The structural unit (C-II) is preferably a structural unit derived from 1-alkyl-1-cycloalkyl (meth) acrylate or a structural unit derived from 2-alkyl-2-adamantyl (meth) acrylate. Structural units derived from -1-cyclopentyl (meth) acrylate, structural units derived from 2-alkyl-2-adamantyl (meth) acrylate are more preferred, and structural units derived from 1-methyl-1-cyclopentyl (meth) acrylate , Structural unit derived from 1-ethyl-1-cyclopentyl (meth) acrylate, structural unit derived from 1-i-propyl-1-cyclopentyl (meth) acrylate, derived from 2-methyl-2-adamantyl (meth) acrylate Structural unit, 2-ethyl-2-adamantyl (meth) acrylate More preferably a structural unit derived from bets.

  As the monomer that gives the structural unit (C-II), among the monomers exemplified as the monomer that gives the structural unit (II) of the [A] polymer, the monomers (2-2) and (2 -3), (2-4), (2-9) and (2-10) are preferred.

  The content ratio of the structural unit (C-II) is preferably 10 mol% or more and 90 mol% or less, more preferably 30 mol% or more and 80 mol% or less, with respect to all the structural units constituting the [C] polymer. 40 mol% or more and 70 mol% or less is more preferable. By making the content rate of a structural unit (C-II) into the said range, the pattern formation property of the said radiation sensitive resin composition for immersion exposure can be improved.

[Structural unit (IV)]
The structural unit (IV) is a structural unit including at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. When the polymer [C] has the structural unit (IV), the adhesion of the resist film formed from the radiation-sensitive resin composition for immersion exposure to the substrate can be enhanced.

  Examples of the monomer that gives the structural unit (IV) include monomers represented by the following formulas (4-1) to (4-14).

  Among the above monomers, the monomer (4-1), the monomer (4-2), and the monomer (4-3) are preferable, and the monomer (4-1) is more preferable.

  The content ratio of the structural unit (IV) is preferably 10 mol% or more and 80 mol% or less, more preferably 20 mol% or more and 70 mol% or less, based on all the structural units constituting the [C] polymer. More preferably, it is more than mol% and less than 60 mol%. By making the content rate of structural unit (IV) into the said range, the adhesiveness with the board | substrate of the resist film formed from the said radiation sensitive resin composition for immersion exposure can be improved.

[Other structural units]
[C] The polymer may have, for example, a structural unit containing a polar group as another structural unit other than the structural unit (C-II) and the structural unit (IV). Examples of the polar group include a carboxy group, a hydroxy group, a cyano group, a nitro group, and a sulfonamide group. Among these, a carboxy group and a hydroxy group are preferable. As a content rate of another structural unit, 30 mol% or less is preferable with respect to all the structural units which comprise a [C] polymer, and 20 mol% or less is more preferable.

  [C] The content of the polymer is preferably 500 parts by mass or more and 10,000 parts by mass or less, more preferably 700 parts by mass or more and 7,000 parts by mass or less, with respect to 100 parts by mass of the polymer [A]. More preferably, it is 1,000 to 4,000 parts by mass.

  [C] The content of the polymer is preferably 70% by mass or more, more preferably 75% by mass or more, and more preferably 80% by mass or more based on the total solid content of the radiation-sensitive resin composition for immersion exposure. Further preferred.

<[C] Polymer Synthesis Method>
[C] The polymer can be synthesized by a method similar to the above-described method for synthesizing the [A] polymer, using a monomer that gives a predetermined structural unit.

  [C] The Mw of the polymer is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, still more preferably 3,000 to 15,000, and more preferably 3,000 to 10 1,000 or less is particularly preferable. [C] By making Mw of a polymer into the specific range, the radiation-sensitive resin composition for immersion exposure can improve lithography performance such as sensitivity and resolution.

  [C] The Mw / Mn of the polymer is preferably 1 or more and 5 or less, more preferably 1 or more and 3 or less, further preferably 1 or more and 2 or less, and particularly preferably 1.2 or more and 1.6 or less. [C] By making Mw / Mn of a polymer into the said range, the said radiation sensitive resin composition for liquid immersion exposure can improve lithography performance, such as a sensitivity and resolution.

<[D] Acid diffusion controller>
The radiation-sensitive resin composition for immersion exposure preferably further contains a [D] acid diffusion controller. The acid diffusion control agent [D] controls the diffusion phenomenon of the acid generated from the acid generator [B] upon exposure in the resist film, and has the effect of suppressing undesirable chemical reactions in the non-exposed areas. Therefore, the radiation-sensitive resin composition for immersion exposure further includes lithography performance such as resolution while maintaining the above-described receding contact angle and the like by further including [D] acid diffusion controller. Can be improved. The inclusion form of the [D] acid diffusion controller in the radiation-sensitive resin composition for immersion exposure is a polymer even in the form of a compound as will be described later (hereinafter referred to as “[D] acid diffusion controller” as appropriate). May be incorporated as a part of or both of these forms.

  [D] Examples of the acid diffusion controller include Nt-alkoxycarbonyl group-containing amino compounds, tertiary amine compounds, quaternary ammonium hydroxide compounds, and the like.

  Examples of the Nt-alkoxycarbonyl group-containing amino compound include Nt-butoxycarbonyldi-n-octylamine, Nt-amyloxycarbonyldi-n-octylamine, Nt-butoxycarbonyldi- n-nonylamine, Nt-amyloxycarbonyldi-n-nonylamine, Nt-butoxycarbonyldi-n-decylamine, Nt-amyloxycarbonyldi-n-decylamine, Nt-butoxycarbonyldicyclohexylamine Nt-amyloxycarbonyldicyclohexylamine, Nt-butoxycarbonyl-1-adamantylamine, Nt-amyloxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-2-adamantylamine, N- t-Amyloxycarbonyl-2-adamanche Amine, Nt-butoxycarbonyl-N-methyl-1-adamantylamine, Nt-amyloxycarbonyl-N-methyl-1-adamantylamine, (S)-(−)-1- (t-butoxycarbonyl ) -2-pyrrolidinemethanol, (S)-(−)-1- (t-amyloxycarbonyl) -2-pyrrolidinemethanol, (R)-(+)-1- (t-butoxycarbonyl) -2-pyrrolidine Methanol, (R)-(+)-1- (t-amyloxycarbonyl) -2-pyrrolidinemethanol, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine, Nt-butoxycarbonylpyrrolidine, Nt-amyloxycarbonylpyrrolidine, N, N′-di-t-butoxycarbonylpyrrolidine Razine, N, N′-di-t-amyloxycarbonylpiperazine, N, N-di-t-butoxycarbonyl-1-adamantylamine, N, N-di-t-amyloxycarbonyl-1-adamantylamine, N -T-butoxycarbonyl-4,4'-diaminodiphenylmethane, Nt-amyloxycarbonyl-4,4'-diaminodiphenylmethane, N, N'-di-t-butoxycarbonylhexamethylenediamine, N, N'- Di-t-amyloxycarbonylhexamethylenediamine, N, N, N ′, N′-tetra-t-butoxycarbonylhexamethylenediamine, N, N, N ′, N′-tetra-t-amyloxycarbonylhexamethylene Diamine, N, N′-di-t-butoxycarbonyl-1,7-diaminoheptane, N, N′-di-t-a Miroxycarbonyl-1,7-diaminoheptane, N, N′-di-t-butoxycarbonyl-1,8-diaminooctane, N, N′-di-t-amyloxycarbonyl-1,8-diaminooctane, N, N′-di-t-butoxycarbonyl-1,9-diaminononane, N, N′-di-t-amyloxycarbonyl-1,9-diaminononane, N, N′-di-t-butoxycarbonyl-1 , 10-diaminodecane, N, N′-di-t-amyloxycarbonyl-1,10-diaminodecane, N, N′-di-t-butoxycarbonyl-1,12-diaminododecane, N, N′- Di-t-amyloxycarbonyl-1,12-diaminododecane, N, N′-di-t-butoxycarbonyl-4,4′-diaminodiphenylmethane, N, N′-di-t-amyloxy Carbonyl-4,4′-diaminodiphenylmethane, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonylbenzimidazole, Nt-amyloxycarbonyl-2-methylbenzimidazole, Nt-butoxycarbonyl-2 -Phenylbenzimidazole, Nt-amyloxycarbonyl-2-phenylbenzimidazole and the like.

Examples of the tertiary amine compound include:
Triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, cyclohexyldimethylamine, dicyclohexylmethylamine , Tri (cyclo) alkylamines such as tricyclohexylamine;
Fragrances such as aniline, N-methylaniline, N, N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, 4-nitroaniline, 2,6-dimethylaniline, 2,6-diisopropylaniline Group amines;
Alkanolamines such as triethanolamine and N, N-di (hydroxyethyl) aniline;
N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, 1,3-bis [1- (4-aminophenyl) -1- Methylethyl] benzenetetramethylenediamine, bis (2-dimethylaminoethyl) ether, bis (2-diethylaminoethyl) ether and the like.

  Examples of the quaternary ammonium hydroxide compound include tetra-n-propylammonium hydroxide and tetra-n-butylammonium hydroxide.

  Of these, Nt-alkoxycarbonyl group-containing amino compounds are preferred, Nt-alkoxycarbonyl group-containing cyclic amine compounds are more preferred, Nt-alkoxycarbonyl-4-hydroxypiperidine is more preferred, N- t-Amyloxycarbonyl-4-hydroxypiperidine is particularly preferred.

  [D] As the acid diffusion control agent, an onium salt compound that is decomposed by exposure and loses basicity as acid diffusion controllability can be used. Examples of such an onium salt compound include a sulfonium salt compound represented by the following formula (5-1), an iodonium salt compound represented by the formula (5-2), and the like.

In the above formulas (5-1) and (5-2), R ^{16 to} R ²⁰ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, or a halogen atom. Z ⁻ and E ⁻ are OH ⁻ , R ²¹ —COO ⁻ , R ²¹ —SO ₃ ^— or an anion represented by the following formula (6). R ²¹ each independently represents an alkyl group, an aryl group or an aralkyl group.

  Examples of the sulfonium salt compound and iodonium salt compound include triphenylsulfonium hydroxide, triphenylsulfonium acetate, triphenylsulfonium salicylate, diphenyl-4-hydroxyphenylsulfonium hydroxide, diphenyl-4-hydroxyphenylsulfonium acetate, and diphenyl. -4-hydroxyphenylsulfonium salicylate, bis (4-t-butylphenyl) iodonium hydroxide, bis (4-t-butylphenyl) iodonium acetate, bis (4-t-butylphenyl) iodonium hydroxide, bis ( 4-t-butylphenyl) iodonium acetate, bis (4-t-butylphenyl) iodonium salicylate, 4-t-butyl Phenyl-4-hydroxyphenyliodonium hydroxide, 4-t-butylphenyl-4-hydroxyphenyliodonium acetate, 4-t-butylphenyl-4-hydroxyphenyliodonium salicylate, bis (4-t-butylphenyl) iodonium Examples thereof include 10-camphor sulfonate, diphenyliodonium 10-camphor sulfonate, triphenylsulfonium 10-camphor sulfonate, 4-t-butoxyphenyl diphenylsulfonium 10-camphor sulfonate, and the like.

  [D] The content of the acid diffusion controller is 20,000 parts by mass or less based on 100 parts by mass of the polymer [A] when the [D] acid diffusion controller is a [D] acid diffusion controller. Is preferably 5 parts by mass or more and 10,000 parts by mass or less, more preferably 10 parts by mass or more and 1,000 parts by mass or less, and particularly preferably 50 parts by mass or more and 500 parts by mass or less.

  [D] The content of the acid diffusion controller is preferably 0.1 part by mass or more and 20 parts by mass or less, and 0.5 part by mass or more and 17 parts by mass or less with respect to 100 parts by mass of the [C] polymer. Is more preferable, and 1 to 15 parts by mass is even more preferable.

  [D] By making content of an acid diffusion control agent into the said range, the shape of the resist pattern obtained from the said radiation sensitive resin composition for immersion exposure improves. [D] One or more acid diffusion control agents may be used.

<[E] solvent>
The said radiation sensitive resin composition for immersion exposure normally contains a [E] solvent. [E] As a solvent, [A] polymer, [B] acid generator, [C] polymer, [D] acid diffusion controller, and other optional components contained as necessary are dissolved or dispersed. There is no particular limitation as long as it is possible. [E] Examples of the solvent include alcohols, ethers, ketones, amides, esters and the like. [E] A solvent can be used 1 type or in mixture of 2 or more types.

Examples of alcohols include:
Methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec-pentanol, tert- Pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n- Nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, furf Alcohol, phenol, cyclohexanol, methyl cyclohexanol, 3,3,5-trimethyl cyclohexanol, benzyl alcohol, monoalcohols such as diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 Polyhydric alcohols such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether and dipropylene glycol monopropyl ether, and the like.

Examples of ethers include
Dialkyl ethers such as diethyl ether, dipropyl ether, dibutyl ether;
Aromatic ring-containing ethers such as diphenyl ether and anisole;
And cyclic ethers such as tetrahydrofuran and tetrahydropyran.

Examples of ketones include:
Acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-iso- Chain ketones such as butyl ketone and trimethylnonanone;
Cyclic ketones such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone;
Diketones such as 2,4-pentanedione and acetonylacetone;
Examples include aromatic ring-containing ketones such as acetophenone.

Examples of amides include:
Chain amides such as N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide;
And cyclic amides such as N, N′-dimethylimidazolidinone and N-methylpyrrolidone.

Examples of esters include:
Methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate Acetates such as 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, ethyl acetoacetate;
Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl acetate Acetates of polyhydric alcohol partial ethers such as ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol monoethyl ether;
Glycol acetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-lactate -Amyl, diethyl malonate, dimethyl phthalate, diethyl phthalate, etc .;
Lactones such as γ-butyrolactone and γ-valerolactone;
Examples include carbonates such as diethyl carbonate and propylene carbonate.

Examples of hydrocarbons include:
Aliphatic carbonization such as n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane, methylcyclohexane Hydrogens;
Fragrances such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene and n-amylnaphthalene Group hydrocarbons and the like.

  Of these, esters and ketones are preferable, acetate esters of polyhydric alcohol partial ethers, cyclic ketones, and lactones are more preferable, and propylene glycol monomethyl ether acetate, cyclohexanone, and γ-butyrolactone are more preferable.

<Other optional components>
The radiation-sensitive resin composition for immersion exposure may contain other optional components such as a surfactant and a sensitizer in addition to the components [A] to [E]. The radiation-sensitive resin composition for immersion exposure may contain one or more other optional components.

[Surfactant]
The surfactant has the effect of improving the applicability, striation, developability and the like of the radiation-sensitive resin composition for immersion exposure. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. Nonionic surfactants such as stearate are listed. Examples of commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, manufactured by Tochem Products), MegaFuck F171, F173 (above, manufactured by DIC), Florard FC430, FC431 (above, Sumitomo 3M) Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, manufactured by Asahi Glass), etc. It is done.

[Sensitizer]
The sensitizer exhibits the effect of increasing the amount of [B] acid generators produced, and has the effect of improving the “apparent sensitivity” of the radiation-sensitive resin composition for immersion exposure. Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines, and the like.

<Method for preparing radiation-sensitive resin composition for immersion exposure>
The radiation-sensitive resin composition for immersion exposure includes, for example, [A] polymer, [B] acid generator, [C] polymer, [D] acid diffusion controller, [E] solvent, and as necessary. And other optional components can be prepared by mixing them at a predetermined ratio. In this case, it is preferable to filter the obtained liquid mixture with a filter having a pore size of about 0.20 μm. As solid content concentration of the said radiation sensitive resin composition for immersion exposure, 0.1 to 50 mass% is preferable, 0.5 to 30 mass% is more preferable, 1 to 10 mass is more preferable. % Or less is more preferable.

<Radiation sensitive resin composition>
The radiation sensitive resin composition of the present invention is
[A] a polymer having a structural unit represented by the above formula (1),
[B] a radiation sensitive acid generator, and [C] a polymer having a smaller fluorine atom content than the [A] polymer,
This [C] polymer has an acid dissociable group.

  According to the radiation-sensitive resin composition, the receding contact angle on the resist film surface can be made larger, smaller after development, and the occurrence of development defects can be suppressed.

<Resist pattern formation method>
The resist pattern forming method is:
A step of forming a resist film with the radiation-sensitive resin composition for immersion exposure (hereinafter, also referred to as “resist film forming step”),
A step of immersion exposure of the resist film via an immersion exposure liquid (hereinafter also referred to as “immersion exposure step”), and a step of developing the resist film subjected to immersion exposure (hereinafter referred to as “development step”). (Also called)
Have
According to the resist pattern forming method, since the above-described radiation-sensitive resin composition for immersion exposure is used, it is possible to form a resist pattern with few development defects while increasing the scanning exposure speed. Hereinafter, each step will be described.

[Resist film forming step]
In this step, a resist film is formed on the substrate using the radiation-sensitive resin composition for immersion exposure. As the substrate, for example, a conventionally known substrate such as a silicon wafer or a wafer coated with aluminum can be used. Further, for example, an organic or inorganic lower-layer antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, or the like may be formed on the substrate.

  Examples of the application method include spin coating (spin coating), cast coating, roll coating, and the like. Note that the thickness of the formed resist film is preferably 10 nm to 300 nm, more preferably 30 nm to 200 nm, and still more preferably 50 nm to 150 nm.

  After applying the radiation-sensitive resin composition for immersion exposure, the solvent in the coating film may be volatilized by soft baking (SB) as necessary. The SB temperature is appropriately selected depending on the composition of the radiation-sensitive resin composition for immersion exposure, but is preferably 30 ° C to 200 ° C, more preferably 50 ° C to 150 ° C. The SB time is preferably 5 seconds to 600 seconds, and more preferably 10 seconds to 300 seconds.

[Exposure process]
In this step, the resist film formed in the exposure step is subjected to immersion exposure via the immersion exposure liquid. This immersion exposure is performed through a predetermined mask and immersion exposure liquid. Examples of the immersion exposure liquid include water and a fluorine-based inert liquid. The immersion exposure liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient as small as possible so as to minimize distortion of the optical image projected onto the film. When the exposure light source is ArF excimer laser light (wavelength 193 nm), water is preferable from the viewpoints of availability and ease of handling in addition to the above-described viewpoints. When water is used, an additive that decreases the surface tension of water and increases the surface activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist film on the wafer and can ignore the influence on the optical coating on the lower surface of the lens. The water used is preferably distilled water.

  The radiation used for the exposure is appropriately selected according to the type of the [B] acid generator. For example, electromagnetic waves such as ultraviolet rays, far ultraviolet rays, X rays and γ rays; charged particles such as electron rays and α rays. Examples include lines. Among these, far ultraviolet rays are preferable, ArF excimer laser light and KrF excimer laser light (wavelength 248 nm) are more preferable, and ArF excimer laser light is more preferable. The exposure conditions such as the exposure amount are appropriately selected according to the blending composition of the radiation-sensitive resin composition for immersion exposure, the type of additive, and the like. In the resist pattern forming method, the exposure process may be performed a plurality of times, and the plurality of exposures may be performed using the same light source or different light sources, but ArF excimer laser light is used for the first exposure. It is preferable to use it.

  It is preferable to perform post exposure baking (PEB) after the exposure. By performing PEB, the dissociation reaction of the acid dissociable group of the polymer in the radiation-sensitive resin composition for immersion exposure can proceed smoothly. As PEB temperature, 30 to 200 degreeC is preferable and 50 to 150 degreeC is more preferable. When the PEB temperature is less than 30 ° C., the dissociation reaction may not proceed smoothly. When the PEB temperature exceeds 200 ° C., the acid generated from the [B] acid generator diffuses to the unexposed area, and it may be difficult to obtain a good pattern.

[Development process]
In this step, the resist film subjected to the immersion exposure in the exposure step is developed. As the developer, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyl Dimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4.3 0.0] -5-Nonene, an alkaline aqueous solution in which at least one alkaline compound is dissolved is preferable. The concentration of the alkaline aqueous solution is preferably 10% by mass or less.

  As a developing method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is left stationary for a certain time (paddle method) ), A method of spraying the developer on the substrate surface (spray method), a method of continuously applying the developer while scanning the developer coating nozzle on the substrate rotating at a constant speed (dynamic dispensing method) Etc.

  After the development, it is preferable to rinse with a rinse solution. As this rinse liquid, water is preferable. When the radiation sensitive resin composition for immersion exposure is used, the receding contact angle after development becomes smaller, so that the developer and the rinsing liquid can be in good contact with the resist film surface, and as a result The occurrence of defects is effectively suppressed.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The measuring method of various physical property values is shown below.

[ ¹ H-NMR analysis and ¹³ C-NMR analysis]
¹ H-NMR analysis and ¹³ C-NMR analysis were performed using a nuclear magnetic resonance apparatus (JNM-ECX400, manufactured by JEOL Ltd.), using CDCl ₃ as a measurement solvent, and tetramethylsilane (TMS) as an internal standard. .

[Mw and Mn measurement]
Mw and Mn of the polymer were measured by gel permeation chromatography (GPC) under the following conditions.
GPC column: 2 G2000HXL, 1 G3000HXL, 1 G4000HXL (manufactured by Tosoh)
Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Column temperature: 40 ° C
Standard material: Monodisperse polystyrene Detector: Differential refractometer

<Synthesis of compounds>
[Synthesis Example 1]
A 1 L three-necked reactor equipped with a dropping funnel and a condenser was charged with 120.9 g of 1,1,1-trifluoro-2-trifluoromethyl-2,4-butanediol, 62.9 g of triethylamine and 200 mL of dichloromethane. Cooled to 0 ° C. in an ice bath. Next, 100.0 g of ethyl 2- (bromomethyl) acrylate was added dropwise over 30 minutes. After completion of dropping, the mixture was stirred at room temperature for 3 hours. Thereafter, the precipitate was removed by filtration, and 200 mL of 1N hydrochloric acid was added to the obtained filtrate to stop the reaction. The obtained organic layer was washed successively with water and saturated brine. The organic layer was then dried over anhydrous magnesium sulfate and concentrated under reduced pressure. Then, it refine | purified by vacuum distillation and synthesize | combined the compound represented by the following formula (S-1) 137.8g (yield 82%).

¹ H-NMR data is shown below.
¹ H-NMR (CDCl ₃ ) δ: 1.31 (t, 3H), 2.27-2.30 (m, 2H), 3.89-3.91 (m, 2H), 4.22-4 .28 (m, 4H), 5.81 (s, 1H), 6.37 (s, 1H)

[Synthesis Example 2]
In Synthesis Example 1, the same procedure as in Synthesis Example 1 was performed except that 92.7 g of methyl 2- (bromomethyl) acrylate was used instead of 100.0 g of ethyl 2- (bromomethyl) acrylate. 124.1 g of the compound represented by S-2) was synthesized (yield 77%).

¹ H-NMR data is shown below.
¹ H-NMR (CDCl ₃ ) δ: 2.29-2.32 (m, 3H), 3.90-3.93 (m, 2H), 4.23-4.30 (m, 4H), 5 .83 (s, 1H), 6.35 (s, 1H)

[Synthesis Example 3]
To a 1 L three-necked reactor equipped with a dropping funnel and a condenser, 23.6 g of 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, N, N′-dibromo-N, N′-1 , 2-ethylenebis (2,5-dimethylbenzenesulfonamide) 55.4 g and dibenzoyl peroxide 24.2 g were dissolved in 1,000 mL of tetrachloroethane and stirred at room temperature for 1 hour. Thereafter, 1,000 mL of water was added to the reaction solution to stop the reaction. The obtained organic layer was washed with saturated brine. Next, the organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure to obtain 22.0 g (yield 70%) of a precursor. Next, a 1 L three-necked reactor equipped with a dropping funnel and a condenser was charged with 14.8 g of 1,1,1-trifluoro-2-trifluoromethyl-2,4-butanediol, 7.1 g of triethylamine, dichloromethane. 200 mL was added and cooled to 0 ° C. in an ice bath. Then, 22.0 g of the synthesized precursor was added dropwise over 30 minutes. After completion of dropping, the mixture was stirred at room temperature for 3 hours. Thereafter, the precipitate was removed by filtration, and 200 mL of 1N hydrochloric acid was added to the obtained filtrate to stop the reaction. The obtained organic layer was washed successively with water and saturated brine. Next, the organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure, and then purified by distillation under reduced pressure to synthesize 25.0 g (yield 80%) of a compound represented by the following formula (S-3).

¹ H-NMR data is shown below.
¹ H-NMR (CDCl ₃ ) δ: 3.85 (S, 1H), 3.90-3.93 (m, 2H), 4.23-4.30 (m, 4H), 5.83 (s) 1H), 6.35 (s, 1H)

[Synthesis Example 4]
In Synthesis Example 1, instead of 120.9 g of 1,1,1-trifluoro-2-trifluoromethyl-2,4-butanediol, 1,1,1-trifluoro-2-trifluoromethyl-2, Except for using 128.9 g of 4-pentanediol, the same operation as in Synthesis Example 1 was performed to synthesize 20.6 g of a compound represented by the following formula (S-4) (yield 75%).

¹ H-NMR data is shown below.
¹ H-NMR (CDCl ₃ ) δ: 1.31 (t, 3H), 1.50 (t, 3H), 2.27-2.30 (m, 2H), 3.54 (q, 1H), 3.89-3.91 (m, 2H), 4.22-4.28 (m, 2H), 5.81 (s, 1H), 6.37 (s, 1H)

[Synthesis Example 5]
In Synthesis Example 3, instead of 23.6 g of 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, 16.8 g of cyclohexyl methacrylate, 1,1,1-trifluoro-2-trifluoromethyl- The same operation as in Synthesis Example 3 was conducted except that 15.8 g of 1,1,1-trifluoro-2-trifluoromethyl-2,4-pentanediol was used instead of 14.8 g of 2,4-butanediol. Then, 27.4 g of a compound represented by the following formula (S-5) was synthesized (yield 70%).

¹ H-NMR data is shown below.
¹ H-NMR (CDCl ₃ ) δ: 1.21-1.56 (m, 10H), 2.27-2.30 (m, 2H), 3.89-3.91 (m, 2H), 4 12-4.20 (m, 1H), 4.22-4.28 (m, 4H), 5.81 (s, 1H), 6.37 (s, 1H)

<[A] Synthesis of polymer>
[A] Monomers used for polymer synthesis are shown below.

[Synthesis Example 6] (Synthesis of Polymer (A-1))
8.77 g (80 mol%) of the compound (S-1) and 1.23 g (20 mol%) of the compound (M-2) were dissolved in 10 g of 2-butanone, and 0.42 g of AIBN was further dissolved to obtain a single amount. A body solution was prepared. Subsequently, a 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. A cooled polymerization reaction solution was poured into 200 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 40 g of methanol, filtered, and dried at 50 ° C. for 17 hours to synthesize a white powdery polymer (A-1) (6.2 g, yield 62). %). Mw of the polymer (A-1) was 4,500, and Mw / Mn was 1.43. As a result of ¹³ C-NMR analysis, the content ratios of the structural unit derived from (S-1) and the structural unit derived from (M-2) were 77.9 mol% and 22.1 mol%, respectively.

[Synthesis Examples 7 to 13] (Polymers (A-2) to (A-6) and (CA-1) and (CA-2))
Each polymer was synthesized in the same manner as in Synthesis Example 6 except that the types and amounts of compounds shown in Table 1 were used. Table 1 shows the content ratio of each structural unit in the synthesized polymer, Mw, and Mw / Mn.

<Synthesis of [C] polymer>
[Synthesis Example 14]
43.1 g (50 mol%) of the above compound (M-1) and 56.9 g (50 mol%) of the compound (M-6) were dissolved in 100 g of 2-butanone, and 4.21 g of AIBN was further dissolved. A body solution was prepared. Subsequently, a 1,000 mL three-necked flask containing 200 g of 2-butanone was purged with nitrogen for 30 minutes, then heated to 80 ° C. with stirring, and the monomer solution prepared above was added dropwise over 3 hours using a dropping funnel. did. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. A cooled polymerization reaction solution was put into 2,000 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 400 g of methanol and then filtered and dried at 50 ° C. for 17 hours to synthesize a white powdery polymer (C-1) (62.3 g, yield 62). %). Mw of the polymer (C-1) was 5,500, and Mw / Mn was 1.41. As a result of ¹³ C-NMR analysis, the content ratios of the structural unit derived from (M-1) and the structural unit derived from (M-6) were 48.2 mol% and 51.8 mol%, respectively.

[Synthesis Examples 15 and 16]
Each polymer was synthesized in the same manner as in Synthesis Example 14 except that the types and amounts of compounds shown in Table 2 were used. The contents of each structural unit of the synthesized polymer, Mw, and Mw / Mn are shown in Table 2.

<Preparation of radiation-sensitive resin composition for immersion exposure>
Each component used for preparation of the radiation sensitive resin composition for immersion exposure is shown below.

[[B] acid generator]
B-1: Triphenylsulfonium nonafluoro-n-butanesulfonate (compound represented by the following formula (B-1))

[[D] acid diffusion controller]
D-1: Nt-amyloxycarbonyl-4-hydroxypiperidine (compound represented by the following formula (D-1))

[[E] solvent]
E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone E-3: γ-butyrolactone

[Example 1] (Preparation of radiation-sensitive resin composition (J-1) for immersion exposure)
[A] 5 parts by mass of (A-1) as a polymer, 100 parts by mass of (C-1) as a [C] polymer, 9.9 parts by mass of (B-1) as an acid generator [D] 7.9 parts by mass as an acid diffusion controlling agent, (E-1) 2,590 parts by mass as (E) solvent, (E-2) 1,110 parts by mass and ( E-3) 200 parts by mass was mixed, and the obtained mixed solution was filtered through a filter having a pore size of 0.20 μm to prepare a radiation-sensitive resin composition (J-1) for immersion exposure.

[Examples 2 to 8 and Comparative Examples 1 and 2] (Preparation of radiation-sensitive resin compositions for liquid immersion exposure (J-2) to (J-8) and (CJ-1) and (CJ-2))
Except having used each component of the kind and compounding quantity shown in Table 3, it operated similarly to Example 1 and prepared each radiation sensitive resin composition for liquid immersion exposure.

<Evaluation>
A resist film was formed on the substrate using each prepared radiation-sensitive resin composition for immersion exposure. The substrate was an 8-inch silicon wafer when measuring the receding contact angle, and a 12-inch silicon wafer on which an underlayer antireflection film (ARC 66, manufactured by Nissan Chemical Industries) was formed when measuring the number of development defects. The following evaluation was performed on each formed resist film. The evaluation results are shown in Table 3.

[Backward contact angle]
With respect to the formed resist film, the receding contact angle was measured by the following procedure using a contact angle meter (DSA-10, manufactured by KRUS) in an environment of room temperature 23 ° C., humidity 45%, and normal pressure.
The DSA-10 needle is washed with acetone and isopropyl alcohol before measurement, and then water is injected into the needle, and a wafer having a resist film formed on the wafer stage is set. The height of the stage is adjusted so that the distance between the resist film surface and the tip of the needle is 1 mm or less, and then water is discharged from the needle to form a 25 μL water droplet on the resist film. While suctioning at a rate of / min for 180 seconds, the contact angle was measured every second. From the time when the contact angle was stabilized, an average value was calculated for a total of 20 contact angles, which were defined as receding contact angles (°).

(Backward contact angle after SB)
After applying each radiation-sensitive resin composition for immersion exposure on an 8-inch silicon wafer, SB was performed at 100 ° C. for 60 seconds to form a resist film having a thickness of 110 nm. The receding contact angle on the resist film surface was defined as “the receding contact angle after SB”.

(Retraction contact angle after development)
After applying each radiation-sensitive resin composition for immersion exposure on an 8-inch silicon wafer, SB was performed at 100 ° C. for 60 seconds to form a resist film having a thickness of 110 nm. Next, development is performed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution for 30 seconds using a GP nozzle of a developing device (Clean Track ACT8, manufactured by Tokyo Electron), rinsing with pure water for 15 seconds, and liquid at 2,000 rpm. The receding contact angle on the resist film surface after being shaken off and dried was defined as “the receding contact angle after development”.

[Number of development defects]
After applying a radiation-sensitive resin composition for each immersion exposure on a 12-inch silicon wafer on which a lower antireflection film (ARC66, manufactured by Nissan Chemical Industries) was formed, SB was performed at 100 ° C. for 60 seconds to obtain a film having a thickness of 110 nm. A resist film was formed. Next, this resist film is used for forming a line and space with a line width of 55 nm using an ArF excimer laser immersion exposure apparatus (NSR S610C, manufactured by NIKON) under the conditions of NA = 1.3, ratio = 0.812, and Crosspore. It exposed through the mask pattern. After the exposure, PEB was performed at 120 ° C. for 60 seconds. Thereafter, the resist film was developed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution, washed with water and dried to form a positive resist pattern. At this time, the exposure amount for forming a line and space having a width of 55 nm was determined as the optimum exposure amount. With this optimum exposure amount, a line and space having a line width of 55 nm was formed on the entire surface of the wafer to obtain a development defect inspection wafer. Note that a scanning electron microscope (S-9380, manufactured by Hitachi High-Technologies Corporation) was used for measuring the resist pattern. The number of development defects on the obtained development defect inspection wafer was measured using a defect inspection apparatus (KLA2810, manufactured by KLA-Tencor). The measured defects were classified into those judged to be derived from the resist and foreign matters derived from the outside. After classification, the total number of resists determined to be derived from resist was defined as “development defect number”. Table 3 shows numerical values of the number of development defects. The development defect suppression property of the radiation-sensitive resin composition for immersion exposure can be judged as “good” when the number of development defects is less than 50 / wafer and as “bad” when the number of development defects is 50 / wafer or more.

  As is clear from the results in Table 3, when the radiation-sensitive resin composition for immersion exposure of the example was used, the receding contact angle was larger after SB than that of the comparative example. It was confirmed that the film was excellent in the change in receding contact angle during immersion exposure and after development. In addition, it was found that development defects are very unlikely to occur according to the radiation-sensitive resin composition for immersion exposure in the examples.

  According to the radiation-sensitive resin composition for immersion exposure and the resist pattern forming method of the present invention, a resist pattern with few development defects can be formed while increasing the scanning exposure speed. Therefore, the present invention can be suitably used for an immersion exposure process, and the productivity can be improved and the quality of a resist pattern to be formed can be improved.

Claims (4)

[A] a polymer having a structural unit represented by the following formula (1):
[B] a radiation sensitive acid generator, and [C] a polymer having a smaller fluorine atom content than the [A] polymer,
The radiation sensitive resin composition in which the [C] polymer has an acid dissociable group.

(In Formula (1), R ¹ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ² is a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms, R ³ is a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a group in which one or more of these are combined with —O—, and R ³ is a hydrogen atom or 1 to 2 carbon atoms. 20 is a monovalent organic group of 20. R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.) [A] polymer, radiation-sensitive resin composition according to claim 1, further comprising a structural unit containing an acid-dissociable group. [D] The radiation-sensitive resin composition according to claim 1, further comprising an acid diffusion controller. [A] a polymer having a structural unit represented by the following formula (1), and
[B] Radiation sensitive acid generator
Forming a resist film with a radiation-sensitive resin composition for immersion exposure containing
A resist pattern forming method comprising: a step of subjecting the resist film to immersion exposure via a liquid for immersion exposure; and a step of developing the resist film subjected to the immersion exposure.

(In Formula (1), R ¹ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ² is a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms, R ³ is a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a group in which one or more of these are combined with —O—, and R ³ is a hydrogen atom or 1 to 2 carbon atoms. 20 is a monovalent organic group of 20. R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.)